title: Purification and characterization of deoxyribonuclease from earthworm Eisenia foetida.
abstract: OBJECTIVE
  To purify a kind of deoxyribonuclease from earthworm Eisenia foetida (named earthworm DNase, EDNase) and study its characteristics.
  
  
  METHODS
  Acetone precipitation, ion-exchange chromatography, high performance liquid chromatography, SDS-PAGE, Capillary electrophoresis isoelectric focusing and MALDI-TOP MS were used for the study.
  
  
  RESULTS
  This purified protocol improved 137-fold purification and 45.6% recovery of enzyme activity. The molecular mass of EDNase was estimated to be 63,000. Mg2+, Mn2+ and Ca2+ were strong inhibitors of EDNase, while Na+ slightly increased the enzyme activity. The enzyme was completely stable in the pH range from 4.4 to 5.2 and had a pH optimum of 4.8. The optimum temperature was 37 degree C and the enzyme was stable up to 40 degree C. The pI of the enzyme was 6.20. Km and Vmax for the enzyme were 1.52 g/L and 4.89 mg/(mL.min), respectively, with calf thymus DNA as substrate. The enzyme was able to degrade chromosomal DNA, linear lambda-bacteriophage DNA as well as supercoiled plasmid DNA, but didn't display any RNase activity.
  
  
  CONCLUSIONS
  This kind of deoxyribonuclease possesses unique characteristics, which is different from the deoxyribonucleases which we have known before.
authors.affiliation: Department of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Jian-lin
authors.initials: JL
authors.lastname: Zhang
authors.forename: Zhi-zhen
authors.initials: ZZ
authors.lastname: Liu
authors.forename: Xiao-yuan
authors.initials: XY
authors.lastname: Wang
authors.forename: Jian-qiang
authors.initials: JQ
authors.lastname: Yao
authors.forename: Jia
authors.initials: J
authors.lastname: Luo
authors.forename: Jian-hua
authors.initials: JH
authors.lastname: Wang
authors.forename: Li-jun
authors.initials: LJ
authors.lastname: Yang
authors.forename: Qi
authors.initials: Q
authors.lastname: Yang
authors.forename: Bo
authors.initials: B
authors.lastname: Niu
mesh_terms: D000818:Animals; D003851:Deoxyribonucleases / Q000302:isolation & purification* / Q000378:metabolism*; D009835:Oligochaeta / Q000201:enzymology*
chemical_list: D003851:Deoxyribonucleases